Spinal surgery can be performed through large incisions or percutaneously, i.e., through small incisions using instruments specifically designed to allow the performance of surgery through small incisions. Such procedures are well known. Percutaneous procedures are often preferred because they are less invasive and leave less external scar tissue. However, some procedures are difficult to perform percutaneously because of the configuration of the devices to be installed.
In the performance of spine surgery for such things as scoliosis, disc removal or replacement, spine fusion, bone grafts and spine deformity or weakness from cancer, metal (used to mean metal alloys and metal) rods are secured to the spine to help support the spine and/or straighten the spine. Rods may also be used to redistribute load on various vertebrae. Rods may be secured to the spine on opposite sides of the spine for extra support and rigidity.
For scoliosis, surgery is used primarily for severe cases or for curves that do not respond to bracing. Surgery has two main goals—to stop a curve from progressing and to correct spinal deformity.
There are various techniques used for scoliosis surgery. One type of surgery involves posterior spinal fusion with instrumentation and bone grafting. This surgery is performed through the patient's back while the patient lies on their stomach. During this type of surgery, the surgeon attaches a metal rod to each side of the patient's spine by using hooks or screws attached to the vertebral bodies. Then, the surgeon fuses the spine with a piece of bone from the patient's hip (a bone graft). The bone grows in between the vertebrae and holds them together and straight. This process is called spinal fusion. The metal rods attached to the spine ensure that the backbone remains straight while the spinal fusion takes place.
The only lateral support for the rods is the vertebral bodies to which the rods are attached and the rods themselves. Additionally, the only support for the screws installed in the bones to support the rods is the bones themselves and perhaps to some extent, the rods and adjacent screws on the same rod. In the treatment spinal curvature as in the treatment of scoliosis, the spine needs to be brought to a less laterally curved condition which is difficult to do in percutaneous surgery since very little of the length of the rods is exposed.
There is thus a need for an improved means to perform back surgery when rods are utilized.